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TL;DR
  • Reference for kustomization.yaml

Kustomization.yaml Reference

Terms:

  • Generators: Provide Resource Config to Kustomize - e.g. resources, bases, secretGenerators.
  • Transformers: Modify Resource Config by adding, updating or deleting fields - e.g. namespace, commonLabels, images.
  • Meta: Configure behavior of Generators and Transformers - e.g. generatorOptions, crds, configurations.

Table of Contents

Name Type Descriptions Guides
bases Generator Add Resource Configs from another kustomization.yaml Bases and Variants
commonAnnotations Transformer Set annotations on all Resources and Selectors. Labels and Annotations
commonLabels Transformer Set labels on all Resources and Selectors. Labels and Annotations
configMapGenerator Generator Generate ConfigMap Resources. Secrets and ConfigMaps
configurations Meta Extend functionality of builtin Transformers to work with additional types (e.g. CRDs).
generatorOptions Meta Configure how ConfigMaps and Secrets are generated.
images Transformer Override image names and tags. Container Images
namespace Transformer Override namespaces on all Resources. Namespaces and Names
namePrefix Transformer Add a prefix to the names of all Resources and References. Namespaces and Names
nameSuffix Transformer Add a suffix to the name of all Resources and References. Namespaces and Names
patchesJson6902 Transformer Patch Resource Config using json patch. Customizing Resource Fields
patchesStrategicMerge Transformer Patch Resource Config using an overlay. Customizing Resource Fields
resources Generator Add Raw Resource Configs. Apply
secretGenerator Generator Generate Secret Resources. Secrets and ConfigMaps
vars Transformer Substitute Resource Config field values into Pod Arguments. Config Reflection

See this example kustomization.yaml

Resource Generators

Resource Generators provide Resource Configs to Kustomize from sources such as files, urls, or kustomization.yaml fields.

bases

bases contains a list of paths to directories or git repositories containing kustomization.yamls.

bases produce Resource Config by running Kustomize against the target. The provided Resource Config will then have Transformers from the current kustomization.yaml applied.

bases are conceptually similar to a base image referenced by FROM in a Dockerfile.

Name Type Desc
base []string List of paths must point to directories or git repositories containing kustomization.yamls.
apiVersion: kustomize.config.k8s.io/v1beta1
kind: Kustomization
bases:
- path/to/dir/with/kust/
- https://github.com/org/repo/dir/

configMapGenerator

configMapGenerator contains a list of ConfigMaps to generate.

By default, generated ConfigMaps will have a hash appended to the name. The ConfigMap hash is appended after a nameSuffix, if one is specified. Changes to ConfigMap data will cause a ConfigMap with a new name to be generated, triggering a rolling update to Workloads referencing the ConfigMap.

Resources such as PodTemplates should reference ConfigMaps by the name ConfigMapGenerator field, and Kustomize will update the reference to match the generated name, as well as namePrefix's and nameSuffix's.

Note: Hash suffix generation can be disabled for a subset of ConfigMaps by creating a separate kustomization.yaml and generating these ConfigMaps there. This kustomization.yaml must set generatorOptions.disableNameSuffixHash=true, and be used as a base. See generatorOptions for more details.

Name Type Desc
configMapGenerator []ConfigMapGeneratorArgs List of ConfigMaps to generate.
ConfigMapGeneratorArgs
Name Type Desc
behavior string Merge behavior when the ConfigMap generator is defined in a base. May be one of create, replace, merge.
env string Single file to generate ConfigMap data entries from. Should be a path to a local env file, e.g. path/to/file.env, where each line of the file is a key=value pair. Each line will appear as an entry in the ConfigMap data field.
files []string List of files to generate ConfigMap data entries from. Each item should be a path to a local file, e.g. path/to/file.config, and the filename will appear as an entry in the ConfigMap data field with its contents as a value.
literals []string List of literal ConfigMap data entries. Each item should be a key and literal value, e.g. somekey=somevalue, and the key/value will appear as an entry in the ConfigMap data field.
name string Name for the ConfigMap. Modified by the namePrefix and nameSuffix fields.
namespace string Namespace for the ConfigMap. Overridden by kustomize-wide namespace field.
apiVersion: kustomize.config.k8s.io/v1beta1
kind: Kustomization
configMapGenerator:
# generate a ConfigMap named my-java-server-props-<some-hash> where each file
# in the list appears as a data entry (keyed by base filename).
- name: my-java-server-props
  files:
  - application.properties
  - more.properties
# generate a ConfigMap named my-java-server-env-vars-<some-hash> where each literal
# in the list appears as a data entry (keyed by literal key).
- name: my-java-server-env-vars
  literals:    
  - JAVA_HOME=/opt/java/jdk
  - JAVA_TOOL_OPTIONS=-agentlib:hprof
# generate a ConfigMap named my-system-env-<some-hash> where each key/value pair in the
# env.txt appears as a data entry (separated by \n).
- name: my-system-env
  env: env.txt

resources

resources contains a list of Resource Config file paths to be customized. Each file may contain multiple Resource Config definitions separated by \n---\n.

Name Type Desc
resources []string Paths to Resource Config files.
apiVersion: kustomize.config.k8s.io/v1beta1
kind: Kustomization
# list of files containing Resource Config to add
resources:
- path/to/resource.yaml
- another/path/to/resource.yaml

secretGenerator

secretGenerator contains a list of Secrets to generate.

By default, generated Secrets will have a hash appended to the name. The Secrets hash is appended after a nameSuffix, if one is specified. Changes to Secrets data will cause a Secrets with a new name to be generated, triggering a rolling update to Workloads referencing the Secrets.

Resources such as PodTemplates should reference Secrets by the name secretsGenerator field, and Kustomize will update the reference to match the generated name, as well as namePrefix's and nameSuffix's.

Note: Hash suffix generation can be disabled for a subset of Secret by creating a separate kustomization.yaml and generating these Secret there. This kustomization.yaml must set generatorOptions.disableNameSuffixHash=true, and be used as a base. See generatorOptions for more details.

Name Type Desc
secretGenerator []SecretGeneratorArgs List of Secrets to generate.
SecretGeneratorArgs
Name Type Desc
behavior string Merge behavior when the Secret generator is defined in a base. May be one of create, replace, merge.
env string Single file to generate Secret data entries from. Should be a path to a local env file, e.g. path/to/file.env, where each line of the file is a key=value pair. Each line will appear as an entry in the Secret data field.
files []string List of files to generate Secret data entries from. Each item should be a path to a local file, e.g. path/to/file.config, and the filename will appear as an entry in the ConfigMap data field with its contents as a value.
literals []string List of literal Secret data entries. Each item should be a key and literal value, e.g. somekey=somevalue, and the key/value will appear as an entry in the Secret data field.
name string Name for the Secret. Modified by the namePrefix and nameSuffix fields.
namespace string Namespace for the Secret. Overridden by kustomize-wide namespace field.
type string Type of Secret. If type is "kubernetes.io/tls", then "literals" or "files" must have exactly two keys: "tls.key" and "tls.crt".
apiVersion: kustomize.config.k8s.io/v1beta1
kind: Kustomization
secretGenerator:
  # generate a tls Secret
- name: app-tls
  files:
    - secret/tls.cert
    - secret/tls.key
  type: "kubernetes.io/tls"
- name: env_file_secret
  # env is a path to a file to read lines of key=val
  # you can only specify one env file per secret.
  env: env.txt
  type: Opaque

Transformers

Transformers modify Resources by adding, updating or deleting fields. Transformers work against Generated Resource Config - e.g.

  • resources
  • bases
  • configMapGenerator
  • secretGenerator

commonAnnotations

commonAnnotations sets annotations on all Resources. commonAnnotations's from bases will stack - e.g. if a commonAnnotations was set in a base, the new commonAnnotations will be added to or override the base commonAnnotations.

Name Type Desc
commonAnnotations map[string]string Keys/Values for annotations.
apiVersion: kustomize.config.k8s.io/v1beta1
kind: Kustomization
commonAnnotations:
  annotationKey1: "annotationValue2"
  annotationKey2: "annotationValue2"

commonLabels

This field sets labels on all Resources. commonLabels's from bases will stack - e.g. if a commonLabels was set in a base, the new commonLabels will be added to or override the base commonLabels.

commonLabels will also be applied both to Label Selector fields and Label fields in PodTemplates.

Note: Because commonLabels are applied to Selectors, they cannot be changed for some objects.

Name Type Desc
commonLabels map[string]string Keys/Values for labels.
apiVersion: kustomize.config.k8s.io/v1beta1
kind: Kustomization
commonLabels:
  labelKey1: "labelValue1"
  labelKey2: "labelValue2"

images

images overrides image names and tags in all [spec.template.]spec.containers.image fields matching the name. This is an alternative to creating patches to change images.

Name Type Desc
images []Image Images to override.
Image

Definitions:

  • name: portion of the image field value before the : - e.g. for foo:v1 the name would be foo.
  • tag: portion of the image field value after the : - e.g. for foo:v1 the name would be v1.
  • digest: alternative to tag for referencing an image.
Name Type Desc
name string Match all image fields with this value for the name
nameName string Replace the image field name with this value.
newTag string Replace the image field tag with this tag value.
digest string Replace the image field tag with this digest value. Includes the sha256: portion of the digest.
apiVersion: kustomize.config.k8s.io/v1beta1
kind: Kustomization
images:
  - name: postgres
    newName: my-registry/my-postgres
    newTag: v1
  - name: nginx
    newTag: 1.8.0
  - name: my-demo-app
    newName: my-app
  - name: alpine
    digest: sha256:24a0c4b4a4c0eb97a1aabb8e29f18e917d05abfe1b7a7c07857230879ce7d3d3

patchesJson6902

Each entry in this list should resolve to a kubernetes object and a JSON patch that will be applied to the object. The JSON patch schema is documented at https://tools.ietf.org/html/rfc6902

Name Type Desc
patchesJson6902 []Json6902 List of patch definitions.
Json6902

Target field points to a kubernetes object by the object's group, version, kind, name and namespace. Path field is a relative file path of a JSON patch file. File contents can be either json or yaml.

Name Type Desc
target Target Target Resource for the patch.
path string Path to json patch file. Maybe json or yaml.

Example patch file:

 - op: add
   path: /some/new/path
   value: value
 - op: replace
   path: /some/existing/path
   value: new value
Target
Name Type Desc
group string Group of the Resource to patch.
kind string Kind of the Resource to patch.
name string Name of the Resource to patch.
namespace string Namespace of the Resource to patch.
version string Version of the Resource to patch.
apiVersion: kustomize.config.k8s.io/v1beta1
kind: Kustomization
patchesJson6902:
- target:
    version: v1
    kind: Deployment
    name: my-deployment
  path: add_init_container.yaml
- target:
    version: v1
    kind: Service
    name: my-service
  path: add_service_annotation.yaml

patchesStrategicMerge

patchesStrategicMerge applies patches to the matching Resource Config (by Group/Version/Kind + Name/Namespace). Patch files contain sparse Resource Config definitions - i.e. containing only the Resource Config fields to add or override. Strategic merge patches are also called overlays.

Small patches that do one thing are best, e.g. modify a memory request/limit. Small patches are easy to review and easy to compose together.

Name Type Desc
patchesStrategicMerge []string Paths to files containing sparse Resource Config.
apiVersion: kustomize.config.k8s.io/v1beta1
kind: Kustomization
patchesStrategicMerge:
- service_port_8888.yaml
- deployment_increase_replicas.yaml
- deployment_increase_memory.yaml

namespace

This field sets the namespace of all namespaced Resources. If the namespace has already been set in the Resource Config, this will override the namespace.

Name Type Desc
namespace String Namespace
apiVersion: kustomize.config.k8s.io/v1beta1
kind: Kustomization
namespace: "my-app-namespace"

namePrefix

namePrefix sets a name prefix on all Resources. namePrefix's from bases will stack - e.g. if a namePrefix was set in a base, the new namePrefix will be pre-prended to the namePrefix in the base.

Fields that references another Resource will also have the namePrefix applied so that the reference is updated.

Name Type Desc
namePrefix String Value to prepend to all Resource names and references.
apiVersion: kustomize.config.k8s.io/v1beta1
kind: Kustomization
namePrefix: "my-app-name-prefix-"

nameSuffix

nameSuffix sets a nameSuffix on all Resources. nameSuffix's from bases will stack - e.g. if a nameSuffix was set in a base, the new nameSuffix will be appended to the nameSuffix in the base.

Fields that references another Resource will also have the nameSuffix applied so that the reference is updated.

Name Type Desc
nameSuffix String Value to append to all Resource names and references.
apiVersion: kustomize.config.k8s.io/v1beta1
kind: Kustomization
nameSuffix: "-my-app-name-suffix"

vars

vars defines values that can be substituted into Pod container arguments and environment variables. This is necessary for wiring post-transformed fields into container arguments and environment variables. e.g. Services names may be transformed by namePrefix and containers may need to refer to Service names at runtime.

Vars are similar to the Kubernetes Downward API in that they allow Pods to reference information about the environment in which they are run.

Variables are referenced from container argument using $(MY_VAR_NAME)

Example:

containers:
- image: myimage
  command: ["start", "--host", "$(MY_SERVICE_NAME)"]
  env:
   - name: SECRET_TOKEN
     value: $(SOME_SECRET_NAME)
Name Type Desc
vars []Var List of variable declarations that may be referenced in container arguments.
Var
Name Type Desc
name string Name of the variable. Referenced by $(NAME).
objref string Reference to the object containing the field to be referenced. ObjRef should use the unTransformed object name
fieldref string Reference to the field in the object. Defaults to metadata.name if unspecified.
apiVersion: kustomize.config.k8s.io/v1beta1
kind: Kustomization
vars:
  - name: SOME_SECRET_NAME
    objref:
      kind: Secret
      name: my-secret
      apiVersion: v1
  - name: MY_SERVICE_NAME
    objref:
      kind: Service
      name: my-service
      apiVersion: v1
    fieldref:
      fieldpath: metadata.name
  - name: ANOTHER_DEPLOYMENTS_POD_RESTART_POLICY
    objref:
      kind: Deployment
      name: my-deployment
      apiVersion: apps/v1
    fieldref:
      fieldpath: spec.template.spec.restartPolicy

Meta Options

Meta Options control how Kustomize generates and transforms Resource Config.

configurations

configurations is used to configure the built-in Kustomize Transformers to work with CRDs. The built-in Kustomize configurations can be found here

Examples:

  • images that should be updated by the images Transformer
  • object references that should be updated by namePrefix, nameSuffix
  • secret and configmap references that should be updated by secretGenerator and configMapGenerator
Name Type Desc
configurations []string List of paths to yaml files containing Kustomize meta configuration.

kustomization.yaml

apiVersion: kustomize.config.k8s.io/v1beta1
kind: Kustomization
configurations:
- mykind_configuration.yaml
commonAnnotations

Specify commonAnnotations in the configuration file to configure the Kustomize commonAnnotations field to find additional annotation fields on CRDs.

Name Type Desc
commonAnnotations []Annotation List of paths to annotations fields.
Name Type Desc
create bool If true, create the annotation field if it is not present on the Resource Config.
group string API Group of the object to add the annotation to. If unset, applies to all API Groups.
kind string Kind of the object to add the annotation to. If unset, applies to all Kinds.
path string Path to annotation field.
version string API Version of the object to add the annotation to. If unset, applies to all Versions.

Built-in examples

mykind_configuration.yaml file referenced by the configurations field

commonAnnotations:
  # set labels at metadata.annotations for all types
- path: metadata/annotations
  # create metadata.annotations if it doesn't exist
  create: true
commonLabels

Specify commonLabels in the configuration file to configure the Kustomize commonLabels field find additional labels and selector fields on CRDs.

Name Type Desc
commonLabels []Label List of paths to label fields.
Name Type Desc
create bool If true, create the label field if it is not present on the Resource Config.
group string API Group of the object to add the label to. If unset, applies to all API Groups.
kind string Kind of the object to add the label to. If unset, applies to all Kinds.
path string Path to label field.
version string API Version of the object to add the label to. If unset, applies to all Versions.

Built-in examples

mykind_configuration.yaml file referenced by the configurations field

commonLabels:
  # set labels at metadata.labels for all types
- path: metadata/labels
  # create metadata.annotations if it doesn't exist
  create: true

  # set labels at spec.selector for v1.Service types
- path: spec/selector
  create: true
  version: v1
  kind: Service

  # set labels at spec.selector.matchLabels for Deployment types
- path: spec/selector/matchLabels
  create: true
  kind: Deployment

  # set labels at  spec...podAffinity...matchLabels for apps.Deployment types
- path: spec/template/spec/affinity/podAffinity/preferredDuringSchedulingIgnoredDuringExecution/podAffinityTerm/labelSelector/matchLabels
  # do NOT create spec...podAffinity...matchLabels if it doesn't exist on the Deployment Resource Config
  create: false
  group: apps
  kind: Deployment
images

Specify images in the configuration file to configure the Kustomize images field find additional image fields on CRDs.

Name Type Desc
images []Image List of paths to image fields.
Name Type Desc
group string API Group of the object to add the label to. If unset, applies to all API Groups.
kind string Kind of the object to add the label to. If unset, applies to all Kinds.
path string Path to label field.
version string API Version of the object to add the label to. If unset, applies to all Versions.

mykind_configuration.yaml file referenced by the configurations field

images:
  # set images at spec.runLatest.container.image for MyKind types
- path: spec/runLatest/container/image
  kind: MyKind
Name References

Specify nameReference in the configuration file for CRDs that reference other objects by name - e.g. Secrets, ConfigMaps, Services, etc.

nameReference registers for a given type, that it is referenced by name from another type - e.g. Secrets are referenced by Pods.

Doing so will configure Generators and Transformers to update the field value with a new name when names are modified - e.g. namePrefix, secretGenerator.

Name Type Desc
nameReference []Reference List of types of objects that are referenced by other objects.
Name Type Desc
group string API Group of the object that is being referenced. If unset, applies to all API Groups.
kind string Kind of the object to that is being referenced - e.g. Secret, ConfigMap.
fieldSpecs []FieldSpec Object types that reference this object type.
version string API Version of the object that is being referenced. If unset, applies to all Versions.
Name Type Desc
group string API Group of the object that contains a reference. If unset, applies to all API Groups.
kind string Kind of the object that contains a reference - e.g. Pod, Deployment*. If unset, applies to all Kinds.
path string Path to the name field that is a reference.
version string API Version of the object that contains a reference*. If unset, applies to all Versions.

Built-In Examples

mykind_configuration.yaml file referenced by the configurations field

nameReference:
# Configure named references to Secret objects to be updated by Transformers and Generators - e.g. namePrefix, secretGenerator, etc
- kind: Secret
  version: v1
  fieldSpecs:
  # v1.Pods that reference a Secret in spec.volumes.secret.secretName will have it updated
  - path: spec/volumes/secret/secretName
    version: v1
    kind: Pod
  # v1.Pods that reference a Secret in spec.containers.env.valueFrom.secretKeyRef.name will have it updated
  - path: spec/containers/env/valueFrom/secretKeyRef/name
    version: v1
    kind: Pod

generatorOptions

generatorOptions modifies behavior of all ConfigMap and Secret generators in the current kustomization.yaml. generatorOptions from bases apply only to the Secrets and ConfigMaps generated within the same kustomization.yaml.

Note It is possible to define generatorOptions for a subset of generated Resources by defining a base to generate the Resources and setting the options there. This supports generating some ConfigMaps with hash-suffixes, and some without.

Name Type Desc
generatorOptions GeneratorOptions Options to define how Secrets and ConfigMaps are generated.
GeneratorOptions
Name Type Desc
labels map[string]string Labels to add to all Resources generated from this kustomization.yaml.
annotations map[string]annotations Annotations to add to all Resources generated from this kustomization.yaml.
disableNameSuffixHash bool If set to true, don't add a hash suffix to any Resources generated from this kustomization.yaml.
apiVersion: kustomize.config.k8s.io/v1beta1
kind: Kustomization
generatorOptions:
  # labels to add to all generated resources
  labels:
    kustomize.generated.resources: somevalue
  # annotations to add to all generated resources
  annotations:
    kustomize.generated.resource: somevalue
  # disableNameSuffixHash is true disables the default behavior of adding a
  # suffix to the names of generated resources that is a hash of
  # the resource contents.
  disableNameSuffixHash: true

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